The present invention relates in general to detecting objects and/or areas. More particularly, the invention provides a method and system for cluster beam-forming. Merely by way of example, the invention is described as it applies to a phased array antenna, but it should be recognized that the invention has a broader range of applicability.
A phased array antenna has been widely used for communications and radar systems. The phased array antenna usually does not mechanically steer antenna directions, and can provide rapid beam scanning. The phased array antenna can also direct transmission power to an intended target and thereby reduce power loss. The directivity of the phase array antenna can be achieved by properly adjusting the relative phases between signals transmitted or received by different antenna elements. These antenna elements can reinforce the transmitted or received radiation in a desired direction.
The phased array antenna usually has a number of subarrays, and each subarray includes multiple antenna elements. For example, a phased array antenna has one hundred and twenty-eight subarrays, and each subarray includes eight antenna elements. Consequently, the phased array antenna has one thousand and twenty-four antenna elements. These antenna elements occupy an area called a phased array antenna panel. The beam pattern of a panel depends on two other beam patterns, namely, the subarray beam pattern and the panel beam pattern. The subarray beam pattern relates to an individual subarray, and the panel beam pattern relates to an array of subarrays.
FIG. 1 is a simplified diagram for subarrays of antenna elements and an array of subarrays for a conventional phased array antenna. A phased array antenna 100 includes subarray beam forming systems 110, 112, and 114, and a panel beam forming system 120. Each subarray beam forming system 110, 112, or 114 includes a subarray of antenna elements and forms a subarray beam pattern. The panel beam forming system 120 forms a panel beam pattern. The subarray beam patterns and the panel beam pattern determine the beam pattern of the phased array antenna 100. Each subarray beam forming system includes various electronic components and can electronically steer the reception or transmission direction of the subarray.
The phased array antenna system usually has the same number of beam-formers within a subarray as the number of beam-formers within a panel antenna, which is also the number of beams provided by the phased array antenna. Each beam of the phased array antenna system is provided by a designated panel antenna beam-former, which is fed by a set of designated subarray beam-formers. The designated subarray beam forming and panel beam forming systems arc usually set to the same reception or transmission direction to produce a single beam. This approach of having a complete set of designated subarray and panel beam formers point to the same direction to provide a single beam usually requires multiple sets of such antenna beam forming systems to produce multiple electronically scanned beams.
Hence it is highly desirable to improve beam-forming techniques.